Typical internal combustion engines use poppet valves arranged in a cylinder head to control air flow into and out of cylinders formed in the main bodies of internal combustion engines. In order to affect combustion of a fuel-air mixture in light of emission standards, it has been known to include some exhaust gas in the fuel-air mixture. Different methods have been employed to provide exhaust gas in the fuel-air mixture. One of the methods provides several opening events for the poppet valves during different stages of a combustion cycle to allow, for example, exhaust gas to enter the cylinder during an intake stroke.
Inasmuch as the poppet valves are typically activated by a camshaft, corresponding changes to the camshaft sometimes have to be made to allow several opening events, which increases their cost of manufacture. Since poppet valves are typically spring biased to a closed position, the camshaft has to work against the bias of the springs for each opening event, which leads to large energy expenditure for opening of the valves.
Alternative internal combustion engines use, for example, spherical rotary intake and outlet valves as shown in U.S. Pat. No. 6,779,504, issued to Coates on Aug. 24, 2004. Coates describes spherical rotary valves arranged in spherical valve chambers formed in a cylinder head to control intake and exhaust of gases into and from a cylinder of an internal combustion engine. Such spherical rotary valves, however, do not allow the provision of an air-exhaust gas mixture in a cylinder of the internal combustion engine.
The present application is directed to overcoming one or more of the problems set forth above.